2cb7b7c03e
The aligned direct-DMA receive path only invalidated the destination buffer before the transfer in stm32_dmarecvsetup(). On the Cortex-M7 the cache can speculatively prefetch into that cacheable buffer between the pre-DMA invalidate and DMA completion, leaving stale lines that shadow the data just written by the IDMA, so the CPU reads a previously cached sector instead of the freshly received data. Invalidate again in stm32_recvdma() once the aligned transfer completes, before the buffer is consumed. The buffer and length are cache-line aligned on this path, so no adjacent memory is affected. This matches the STM32 AN4839 guidance that a cache invalidate is required after DMA completion and before the CPU reads the updated region, not only before the transfer starts. A related instance of the same "invalidate too early" defect on STM32H7 SPI DMA is tracked in apache/nuttx#11594. Root-caused on a PX4 FMUv6C (STM32H743) board where MAVLink ULog downloads were intermittently corrupted: forensic diffing showed corrupted windows were exactly 32 bytes (the D-cache line size), cache-line aligned, and byte-for-byte equal to the previous 512-byte SD sector cached in the FAT single-sector buffer. Disabling the D-cache made the corruption disappear, isolating the defect to cache coherency. After this fix, downloaded files matched the source file byte-for-byte (sha256 identical) across a 5.8 MB log spanning thousands of sectors. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Yang-Rui Li <yang77567789@gmail.com> |
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| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.